I am trying to get Cisco Unified SIP Proxy working in our environment as a load balancer for our SIP traffic, but I have had difficulty finding a good Architecture document.  I looked for a SRND type document for CUSP 8.5, but I only see install guides and a few configuration examples.  Does anyone have a working CUSP configuration that I can see an example of?  I have a very simple configuration that I need to setup, but I am struggling to get a request through.  My call flow is as follows:
 
SIP Invite (direct from eyebeam client or SIP provider) --> CUSP --> CUBE --> CVP --> VXML GW (for prompting)
 
I am getting the invite to the CUSP, but I am unable to trigger an invite to the CUBE/CVP that will send the call to CVP for prompting.
 
Any ideas?